Grimace is a character featured in McDonaldland commercials. He is a large, purple anthropomorphic being of indeterminate species with short arms and legs. He is known for his slow-witted demeanor. His most common expression is the word "duh" before every sentence.

Originally, Grimace was the "Evil Grimace", with two pairs of arms with which to steal milkshakes. After that first campaign, the character was revised to be one of the "good guys", and his number of arms was reduced by two. These commercials and merchandise generally portray him as a well-meaning simpleton, whose clumsy antics provide a comic foil to Ronald McDonald. The character was retained after the streamlining of the characters in the 1980's and was one of the few members to also be retained until the end of the McDonaldland commercials.

In a 1999 commercial for McDonald's, Grimace has two aunts named Millie and Tillie, whom Ronald mistakes for actual ants while on a picnic.

While many family members have been mentioned, most heavily seen and mentioned is Uncle O'Grimacey who came one month every year, around St. Patrick's Day in March, to bring Shamrock Shakes. He has an unnamed mom, an unnamed dad, a grandma named "Winky", a great, great grandma named Jenny Grimace, and a possible brother named King Gonga (who rules over all Grimaces).

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